Automated gate mechanisms are popular means for securing access to various locations, such as outdoor areas, buildings, or rooms. In the typical embodiment, a gate is pivoted, slid, or otherwise translated across a pathway and access to the area, building, or room beyond the gate is controlled by the position of the gate relative the pathway. In an automated environment, such equipment can provide the necessary security to the given area while minimizing the need for participation by security personnel.
In commercial and industrial settings, it is common to utilize large, fixed-area, slide gates to block roadways, walkways, sidewalks, and other pathways. These slide gates may include chainlink fencing, parallel bars, or other barriers to provide a gate structure sufficient to preclude unwanted passage of individuals beyond the gate when closed. Such gates are typically controlled by a drive mechanism adapted to slide the gate transversely across the pathway from an open to a closed position and vice versa. The drive mechanism typically includes a motorized drive wheel adapted to frictionally engage a portion of the gate itself. By rotating the drive wheel in one direction, the gate is translated across the path and by rotating the drive wheel in the opposite direction the gate is removed from the path.
Slide gates have an inherent problem in precisely stopping the movement of the gate. Industrial size gates are typically quite large and heavy and produce a sizable amount of momentum during movement. Because of this momentum, slide gates typically coast (i.e., continue to slide) a short distance after the drive mechanism has been deactivated. This coasting generally occurs in relatively consistent amounts; however, coasting distances may be affected by foreign objects disposed on the gate, such as ice formations, which increase the weight and thus the momentum of the gate during movement.
It is has been known in the industry to position a fixed rigid post in the path of the gate member. This post is designed to limit movement of the gate by blocking the path of travel of the gate at a given point and thereby defining the maximum amount of travel in that direction. Such rigid posts effectively prevent excess coasting of the gate; however, they have several disadvantages. Fixed rigid posts abruptly limit the movement of the gate. Upon impact with the post, vibrations are transmitted to the various components of the gate mechanism, such as the drive and support systems. These vibrations may directly damage these components when a single impact of sufficient degree is encountered. Additionally, repetitive impacts of a lesser degree eventually begin to weaken or otherwise adversely effect the components.
There is thus a need in the industry to provide a means for braking a slide gate in a controlled manner which does not cause an abrupt cessation of gate movement and its accompanying vibration.